The invention concerns a rotatable disc arrangement as a seating surface for physically handicapped people, with a bottom plate, a top plate pivot mounted to this, an upholstery pad centrally arranged on said top plate, and a removable, circular-contoured retaining ring which is attached to the top plate and engages over both the circumferential rim of the upholstery pad and the outer rim of the top plate.
Such a rotatable seat is disclosed in EP-B-0364746. The retaining ring in this case comprises a number of circumferentially adjacent individual ring segments which feature at their bottom latching pins which engage in, and can be disengaged from, corresponding holes in the rotatable top plate. A retaining ring manufactured in one piece would give rise to fitting problems because the top plate, owing to the requisite sliding properties, must consist of a plastics material other than that of the retaining ring, and owing to the different temperature expansion coefficients, would cause fitting deficiencies in respect of the requisite precise engagement of the retaining ring over the top plate.